The invention relates generally to systems for cooling internal combustion engines and more particularly to such systems which employs engine lubricating oil as a coolant.
Two important objectives of an engine cooling system are to hold engine lubricating oil to a temperature at which it remains effective and to minimize temperature gradients in the cylinders. If lubricating oil temperature is excessively high, it loses its effectiveness and excessive engine wear results. Temperature gradients in the cylinders distort the shape of the cylinder walls. This results in accelerated wear, increased oil consumption and greater discharge of undesirable engine emissions. Avoiding these problems is particularly difficult in an air-cooled engine.
It is known to employ engine lubricating oil as a coolant to supplement water and air cooling systems. See, for example, U.S. Pat. Nos. 2,691,972, 4,702,204 and 4,813,408 pertaining to water-cooled engines. The engine disclosed in U.S. Pat. No. 4,928,651 air-cools lubricating oil in a pressure lubrication system.
There is a need for a more effective, simpler and lower cost system for employing lubricating oil as part of an engine cooling system.